The present invention relates to the improvement of bearings such as rolling bearings and rod end bearings, having a shaft center tilt mechanism and rotary mechanism that are mutually independent.
Up to now rod end bearings have, generally, been used as bearings for aircraft use. The conventional rod end bearing 1 shown in FIG. 6 is provided with rolling elements 2 (the illustrated example is a roller), and the inner race 6 which is supported by the main body 4 and is capable of being rotated. Furthermore, in order to prevent the leaking of lubrication oil filled in the inner part of the bearing, the bearing is sealed with a seal 3. Additionally, in the illustrated example, a shield 5 is also fixed to the outer race 4a integrated with the main body 4. At the time of the rotation and at the time of the tilting of the inner race 6 with respect to the outer race 4a, the seal 3 and shield 5 have a sliding relationship. Here, the sealing between the seal 3 and the shield 5 is ensured, mainly, by means of the adhesive strength due to the elasticity of the seal 3.
Another bearing, commonly used in the industry, is the self-aligning type bearing 7 which has a shaft center tilt mechanism, as shown in FIG. 7. This self-aligning type bearing 7 uses a rolling element 8 (the illustrated example is a ball) as shown in FIG. 7, and has a sealed rolling bearing structure that provides a shield 11 and seal 12 between the inner race 9 and the outer race 10 in order to prevent leaking of the lubrication oil filled in the inner part of the bearing. In the example of FIG. 7, the shield 11 fixed to the outer race 10 has the function of holding the seal 12. The sealed relationship between the spherical surface 9a of the inner race 9 and the seal 12 is mainly ensured by the adhesive strength due to the elasticity of the seal 12. Furthermore, bearings without the seal structure are also widely used in both rod end bearings and self-aligning type bearings.
The above-mentioned bearings each have a shaft center tilt mechanism, which is a mechanism that changes the relative angle of the inner race shaft center and the outer race shaft center. For this reason, seals 3 and 12 in FIGS. 6 and 7 respectively, are mainly selected for the purpose of obtaining a highly sealed nature in response to the changes of the tilt angles of the shaft centers. This selection emphasized sliding resistance and high durability, unlike seals of ordinary radial ball bearings. Use of the above-mentioned former rod end bearings 1 and self-aligning type bearings 7 is complicated because the seal function necessary in high speed, long duration and continuous rotation is not provided and, under conditions in which regular maintenance could not be done, the danger of a lubrication oil leak is always possible.
Furthermore, as for the above-mentioned former rod end bearings 1 and self-aligning type bearings 7, regardless of the tilt angle of the shaft center, in order to heighten the sealing property of seals 3 and 12, it is also necessary for the sliding area to become larger, and, at the time of high speed rotation, this large sliding area causes greater noise, friction and “wear and tear”.
On the other hand, in the case of rod end bearings without the seal structure, problems attributable to seals, of course, did not arise, but sufficient lubricity could not be obtained, and making a shaft center tilt mechanism with a compatible high speed rotation mechanism had been regarded as difficult.
In order to make the tilt and rotary mechanisms compatible, the bearing structure became extremely complex and an increase in cost, and the difficulty of maintaining rod end bearings and self-aligning type bearings could not be avoided.